The present invention relates to a drainage valve unit, and more particularly to a drainage valve unit including a valve body defining a drain passage therein and a valve member for opening and closing the drain passage, the valve member being actuatable toward its open position in a single operation from outside of the drainage valve unit for thereby discharging a drain.
As is well known in the art, fluid-pressure devices, such as air filters, have a drainage mechanism, i.e., a drainage valve unit, disposed on the bottom wall of the device for discharging out a liquid separated from air within the device.
FIGS. 1 and 2 of the accompanying drawings illustrate conventional drainage valves by way of example.
The drainage valve shown in FIG. 1 has a platelike valve member 3a for opening and closing a drainage valve port 2a defined in the bottom wall of a device 1 such as a filter. An annular seal 4a is positioned underneath the valve member 3a, from which there extends an operating rod 5a having a predetermined length projecting outwardly. The outwardly projecting end portion of the operating rod 5a is surrounded by a tubular resilient member 6a.
Under normal condition, the valve nmmber 3a is displaced downwardly by a high-pressure fluid introduced into the device 1 for automatically closing the valve port 2a. When a drain is collected in the device 1, the outwardly projecting end portion of the operating rod 5a is laterally pushed through the resilient member 6a in the direction of the arrow (FIG. 1). The valve member 3a is then tilted a certain angle to define a gap between the valve member 3a and the seal 4a, allowing the collected drain to be discharged out through the valve port 2a.
The drainage valve shown in FIG. 2 includes a plate-like valve member 3b for opening and closing a valve port 2b defined in the bottom wall of a device 1. An annular seal 4b is disposed underneath the valve 3b, to which a downwardly extending operating rod 4b is fixed. The operating rod 4b is normally urged downwardly as shown in the direction to close the valve member 3b by a coil spring 7 disposed around the operating rod 4b.
Under normal condition, the valve port 2b is closed by the valve member 3b urged downwardly under the resilient force of the coil spring 7. When a drain is collected in the device 1, the outwardly projecting end portion of the operating rod 5b is pushed in the direction of the arrow (FIG. 2) against the resiliency of the coil spring 7. As a consequence, the valve member 3b is moved upwardly to open the valve port 2b, drawing out the drain
The drainage valve shown in FIG. 1 is disadvantageous in that since the valve member 3a is sealed under the pressure within the device 1, the sealed condition will be made unstable to cause a fluid leakage if the device 1 is used under a low fluid pressure or no fluid pressure. The problem with the drainage valve shown in FIG. 2 is that because the valve member 3b is opened by pushing the operating rod 5b vertically, i.e., in the direction along the valve port 2b, the drain discharged from the valve port 2b falls on the operator's hand when the valve is opened.